U.S. patent number 7,506,721 [Application Number 11/595,204] was granted by the patent office on 2009-03-24 for convertible folded horn enclosure.
Invention is credited to Dana A. Moore.
United States Patent |
7,506,721 |
Moore |
March 24, 2009 |
Convertible folded horn enclosure
Abstract
A low frequency exponential bass horn enclosure employing a
large area unitary throat pathway, bifurcated at a substantially
parabolic rearward channel wall, convertible to a front-loaded or
rear-loaded configuration by the use of interchangeable parts, with
driver access from the front. Intended for corner placement,
however, fully enclosed horn channel allows for floor use. The
axially-centered throat expands vertically, exhausts rearward, and
is bifurcated at the back of the enclosure with two hard reflection
points, comprising a single fold, in which the vertically arranged
horn terminus exhausts with a forward-canted splay angle around a
partially rectangular back chamber.
Inventors: |
Moore; Dana A. (Bothell,
WA) |
Family
ID: |
39368122 |
Appl.
No.: |
11/595,204 |
Filed: |
November 10, 2006 |
Prior Publication Data
|
|
|
|
Document
Identifier |
Publication Date |
|
US 20080110692 A1 |
May 15, 2008 |
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Current U.S.
Class: |
181/156; 181/148;
181/152; 181/177; 181/199; 381/337; 381/338; 381/339; 381/340;
381/341; 381/345; 381/352 |
Current CPC
Class: |
H04R
1/2865 (20130101); H04R 1/30 (20130101) |
Current International
Class: |
H04R
1/02 (20060101); G10K 11/28 (20060101) |
Field of
Search: |
;181/199,156,177,152,148
;381/345,337,338,339,340,341,352 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Benson; Walter
Assistant Examiner: Luks; Jeremy
Claims
I claim:
1. In a horn loudspeaker for the low frequency range; an enclosure
comprising: a plurality of vertical baffles arranged in sealed
relation to form a substantially parabolic wall, arranged with the
center thereof being most rearward, and the ends thereof being most
forward, defining the outside boundary of an expanding column of
air, a second plurality of baffles, spaced forward from said
rearward wall, at least one of said baffles being adapted with at
least one aperture, and including vertical baffles arranged to
parallel the axis at the focus of said parabolic wall, defining a
primary section of expanding air column which expands predominately
vertically from said each aperture and exits rearward along the
central horizontal axis of said rearward wall, and further
including baffles which define the inner boundaries of said
expanding column, at least one sound source, means for turning said
primary air column at the junction of said exit and said rearward
wall into said expanding column boundaries, and means for
completing an air chamber for said sound source and thereby
completing said expanding column.
2. In a horn loudspeaker as set forth in claim 1, wherein said
sound source consists of at least one electro-acoustic transducer
adapted to cooperate in sealed relation with said each
aperture.
3. In a horn loudspeaker as set forth in claim 1, wherein said
plurality of baffles includes two vertical side baffles arranged
with corresponding angles and spaced from said rearward wall as
determined by an exponential flare rate, partially completing said
expanding column.
4. In a horn loudspeaker as set forth in claim 1, wherein said
completing means includes a top, bottom, front, and side baffles in
sealed relation with said second plurality of baffles, said
apertured baffle, and said rearward wall.
5. In a horn loudspeaker as set forth in claim 4, wherein said
front baffle is adapted with at least one aperture, each said front
panel aperture being sealed in operating relation by an
electro-acoustic transducer.
6. In a horn loudspeaker as set forth in claim 1, wherein said
turning means consists of splitting wedges, each having hard
surfaces angled to reflect sound waves from said primary column
sideways in opposite directions, engaged with said rearward wall
and arranged to divide said primary column equally, turning said
sound waves horizontally into said expanding column boundaries.
7. In a horn loudspeaker as set forth in claim 6, wherein said
turning means further includes the angle at which said first
plurality of baffles presents in proximate relation with said
splitting wedges, providing a second reflection, whereby the angle
of said second reflection presents the best axial path of said
sound waves through said expanding column boundaries.
8. A horn loudspeaker for the reproduction of low frequency sound
waves comprising: a bottom and top panel of substantially
triangular cross-section, being adapted along the rearward edges
opposite of a base forming a substantially parabolic contour, a
center axis thereof being the widest point front to back, a
plurality of panels vertically arranged side to side, engaged with
said parabolic contour on said top and bottom panels, forming a
concave-shaped rearward wall, said wall having center portions
proximate to said center axis adapted and arranged to reflect sound
waves traveling perpendicular to said center axis substantially
along said rearward wall in opposite directions from said center
axis, two vertical panels, arranged parallel to said center axis
and equally spaced from the forward-most outer sides of said
rearward wall and forward of said rear wall, aligned with the
forward edge of said top and bottom and engaged therewith, therein
partially defining the horn terminus, and sized to house at least
one sound source. a further assembly of panels, arranged rearward
of said vertical housing panels and forward of said rearward wall,
arranged perpendicular to said rearward wall along the center axis
of said top and bottom panels, defining a vertically expanding
throat channel for said sound source, and exhausting along the
center axis of said concave-shaped wall, means for completing
expanding terminal channels cooperating with said rearward wall,
reflecting means positioned at the rear of said center axis of said
concave-shaped wall to equally bifurcate said throat channel
horizontally, at outward right angles from said center axis, a
removable front panel, vertically arranged, engaged with said
housing assembly panels and front edges of said top and bottom
panel, and means for transmitting sound into said throat
channel.
9. A horn loudspeaker as set forth in claim 8, wherein said
completing means includes a plurality of panels arranged vertically
in sealed engagement with said further assembly and said housing
assembly, cooperating with said rearward wall and spaced therefrom,
defining the frontward portion of a substantially exponential
horizontally flaring channel, completing an air chamber for said
sound source, and thereby completing said terminal channels.
10. A horn loudspeaker as set forth in claim 9, wherein said sound
source consists of at least one sound transducer.
11. A horn loudspeaker as set forth in claim 10, wherein said
transmitting means includes at least one vertically arranged panel
engaged with said throat channel, having at least one aperture
therein, adapted to cooperate in sealed engagement with said sound
transducer, thereby transmitting sound from said sound transducer
to said throat channel therebeyond.
12. A horn loudspeaker as set forth in claim 10, wherein said
transmitting means includes at least one vertically arranged panel
engaged with said throat channel, having at least one aperture
therein, thereby transmitting sound from said sound source to said
throat channel therebeyond.
13. A horn loudspeaker as set forth in claim 12, wherein said
transmitting means further includes said front panel, apertured and
adapted to cooperate in sealed engagement with said sound
transducer, thereby transmitting sound from the rear of said sound
source to said apertured panel, through said air chamber, and
through said each aperture to said throat channel therebeyond.
Description
BACKGROUND OF THE INVENTION
The present invention relates to loudspeaker enclosures of the low
frequency exponential folded horn type primarily intended for
corner placement, however is capable of free-standing use as
needed. In particular, the present invention features a relatively
large-area unitary throat pathway which is bifurcated horizontally
at the rear of the enclosure, and exhausts in a relatively forward
direction.
The Klipsch and Delgado AES paper, "A Revised Low-Frequency Horn of
Small Dimensions", Vol. 48, No. 10, October 2000, describes a dual
12-inch driver folded horn enclosure featuring throat bifurcation
of the horn channels which are horizontally folded. A defining
feature of the device is the forward-canted terminal channels
exiting on each side of a central planar baffle. The use of
forward-canted exit splay angles is explained as providing an
increase in upper band pass frequency response by more direct wave
propagation to the audience. Due to the throat bifurcation, the
access opening to the drivers is required to be on both the top and
bottom of the enclosure. The device is configured specifically for
a particular driver with explicit parameters.
Another prior art example is my previous U.S. Patent Application
Pub. No. 2005/0276431 titled "Top-Loading Folded Corner Horn" which
also features a bifurcated-throat horn pathway which folds
exclusively in the horizontal plane, however, it does not
incorporate forward-canted exit channels, instead, it exits along
the side walls of the corner. The indirect exit channel
splay-angles do provide a physical limitation to the upper
frequency limit in which it can propagate without apparent
distortion. In order to achieve an even higher crossover point as
compared to my previous invention where the limit appears to be 600
Hz, the use of forward-angled exit channels to allow a more direct
path to the listening position is seemingly required. The inclusion
of forward-canted exit channels bears with it the added
complication and weight of including external side walls to fully
enclose the horn pathway. Several factors also enter into the
contemplating the benefits of such an addition would make to the
single 15-inch driver device. For instance, the built-in outer side
walls would free the enclosure from requiring external planar
boundaries to be in close proximity. This allows for a more
generalized placement for the enclosure, while still allowing for
1/8th space placement for achieving the maximum low frequency
response, however, it also would greatly increase the overall
weight and the-complexity of construction, for relatively little
increase in utility.
The increased capabilities presented by the use of dual drivers
also provides useful benefits, such as providing wiring options
which effect efficiency and power handling capabilities, overall
sound pressure levels, and a naturally shorter horn path length for
a given low frequency cutoff (Fc) due to a larger effective throat
size. It is well known in the art that horn pathway lengths below a
certain division of wavelength will suffer from variances in
reactance and subsequently produce peaks in the response unless the
reactance is properly annulled. The horn path length is dependent
on the mouth size, throat size and the chosen flare rate. The U.S.
Pat. No. 4,210,233 to Gillum et al., teaches the minimum mouth size
[area] for corner placement can be as small as 1/12 wavelength [in
diameter] if the driver is properly annulled. It can be assumed
that the horn path length is also, as a matter of course, shortened
if the throat size and flare rate remains unchanged. Conversely,
horns with large throat areas, proper mouth sizes, and having short
pathway lengths require reactance annulling due to the short
pathway lengths involved in order to maintain a relatively flat
response over the operating band pass.
A particular drawback of using dual 15-inch diameter drivers is
that the overall footprint of the device must be increased to
accommodate a relatively large (78 square inch) throat area per
driver especially if bifurcated at the throat. The use of smaller
throat cross-section channels would tend to limit the maximum sound
pressure level due to air overload distortion, and possibly require
the use of smaller diameter drivers to compensate. This problem is
typically overcome by employing a rapid flare rate at the throat to
modify the effects of excessive reactance that a more confined
flare rate (of lower Fc) of a relatively small channel
cross-section would embody.
The ability to achieve lower distortion, in a general sense, is
that large throat cross-sections can allow for higher air velocity
transit compared to a more restricted channel, and therefore throat
overload distortion limits are relegated to the more extreme end of
the performance curve.
Another consideration that particularly effects front-loaded horns
in general is thermal voice coil overload or failure in sustained
high sound pressure level (SPL) use. This aspect is compounded in
the case of dual-drivers in a sealed back chamber, and may be
exacerbated by the tendency of modern high wattage drivers
requiring smaller back chamber air volumes than in the past for
reactance annulling purposes. It seems advisable that, in the case
of high wattage drivers in a infinite baffle configuration and used
for prolonged periods at a high sound pressure level (SPL), should
be provided an adequate means of cooling the voice coils, such as
conducting the generated heat to a heat-sink assembly located
preferably outside the back chamber. This object, while technically
achievable in the case of a bifurcated-throat design such as the
previously cited prior art designs, may not be economically
practical due to the complications imposed by the position of the
driver(s).
Considerations of footprint size are probably most important in
domestic use, however, overall footprint size can also be seen to
be inextricably related to enclosure weight, a definite factor in
public address use where portability is perhaps the major concern.
Enclosures with the best balance of size, weight and performance
capability would seem to be the most desirable, regardless of the
application. In public-address (PA) including live music
applications where higher SPL's are generally desirable, the use of
additional bracing for preventing internal enclosure wall vibration
adds weight to the enclosure, and effects portability. The tradeoff
for domestic situations seems to be that low frequencies with
relatively high efficiencies typically means a larger enclosure,
with the attendant larger footprint, and the tradeoff for PA use is
that achieving high SPL's typically means heavier (or multiple)
enclosures are required.
For PA applications, it is reasonable to assume that multiple
smaller-volume cabinets (for stacking) allow for easier porting and
packing for transportation purposes than a comparable single,
larger-volume cabinet would. However, it seems reasonable for
domestic situations, where semi-permanent placement is assumed, and
perhaps appearance is an important consideration, that a single
large-volume cabinet would be more desirable.
Home Theater (HT) market considerations conceivably fall somewhere
in between the typical domestic use, such as a living room, and a
PA application. It is typically a much smaller venue than a PA
application, but shares some of the same issues, such as overall
clarity, maximum SPL, and the presentation of the human voice. The
HT market may include less concern for appearance than would the
typical domestic situation, for instance, black finishes seem to be
preferred as movies tend to be viewed in darkened spaces. Overall
footprint size may also be less of a concern when a dedicated HT
space is involved. The dynamic soundtracks typical of digital media
may require prolonged periods of intense SPL's than common in
domestic use, such as listening to high-fidelity (HI-FI) music
exclusively. In particular, it can be assumed that the requirements
of reproducing highly dynamic sound effects impose somewhat
different demands on loudspeaker systems than does music alone.
A loudspeaker enclosure capable of reproducing the low frequency
dynamic range available with current digital technology, at
relatively high sound pressure levels, if needed, with low
distortion, employing a relatively small footprint, and which
allows for public address, home theatre, use as musical instrument
speakers, and domestic high fidelity use would be highly
desirable.
SUMMARY OF THE INVENTION
It is an object of the present invention, in one embodiment, to
provide a horn enclosure which allows for conversion to or from
front-loaded or rear-loaded operation without modification through
the use of interchangeable parts. It is a further object to provide
an increase in power handling and sustained high output capability
along with an optional facility for-cooling the voice coil for use
in high output applications. It is a further object of the current
invention to utilize a footprint comparable to the prior art
examples cited previously. Another object is to preserve waveform
phase integrity as much as possible by reducing the number and
severity of folds in the horn pathway as compared to the previously
cited bifurcated prior art examples. A still further object is to
allow for the ability to use a variety of available drivers to meet
specific performance requirements as desired. It is another object
of the preferred embodiment to vary the internal back chamber
volume via baffle cutouts and plugs to add or subtract specific
volumes of void area space to or from the back chamber volume,
allowing for the ability to adjust the back chamber volume (Vb) to
a general value as needed within the limits of the cavities
involved. Further objects and advantages will become apparent in
the remainder of the present disclosure.
The current invention departs from the previously cited prior art
examples in that it maintains a unitary throat pathway of
relatively large cross-section area, suitable for using 15-inch
diameter drivers in a symmetrical dual configuration. The unitary
horn pathway is bifurcated at the rear of the enclosure and follows
a substantially exponential flare to the exit channels, which are
canted slightly inward to provide a more direct path to the
audience, allowing for extended upper bass frequency propagation.
The throat channel is arranged with a horizontal axis and exhausts
rearward, dividing the enclosure vertically along the central axis,
with access to the back chamber being from the front of the
enclosure.
The present invention has the design goal of a low frequency cutoff
(Fc) of 38 Hz. The horn terminal exit size is approximately 800
square inches in area, which is appropriate for 1/8th space (corner
placement). For 1/2 space (floor) placement, such as in PA use, the
overall low frequency response would be comparatively degraded, as
is typical of foreshortened horns, however the overall quality of
the response would still be more than adequate for reproducing
vocals where the extreme low frequencies are not usually
present.
The disclosed invention has a footprint that uses approximately
261/2 inches from the rear of the enclosure to the outside edge of
the front panel and an overall width of approximately 393/4 inches.
The overall height of the invention is approximately 39 inches. The
overall size and footprint of the invention is consistent with the
sizes of the prior art examples previously referenced.
The preferred front-loaded embodiment uses full-channel hard
surface reflectors to aid in maintaining phase relationships of the
given waveform. It is intended to provide the least tortuous horn
pathway possible for the waveform to travel within the limitations
imposed by footprint size constraints, and to that end,
incorporates a single fold comprised of two controlled reflection
surfaces.
The current invention incorporates fully enclosed horn channels
which allows its placement away from walls when desired, however,
the low frequency response would be optimized when placed in a
corner.
The present invention is intended to maximize versatility for
high-sensitivity domestic HI-FI, HT, and PA applications where high
output is desired in a relatively small enclosure.
DESCRIPTION OF THE DRAWINGS
FIG. 1 is a sectional view from line 1-1 of FIG. 2 of the preferred
front-loaded embodiment of the invention with the horizontal
bracing elements not shown.
FIG. 2 is a front elevation view of the preferred front-loaded
embodiment.
FIG. 3 is a sectional view from lines 3-3 of FIGS. 1 and 2 of the
preferred front-loaded embodiment.
FIG. 4 is a sectional view from line 4-4 of FIG. 3 of the preferred
front-loaded embodiment showing the horizontal bracing
elements.
FIG. 5 is a front elevation view of the half-height alternative
front-loaded embodiment.
FIG. 6 is a sectional view from line 6-6 of FIG. 5 of the
half-height alternative front-loaded embodiment.
FIG. 7 is a front elevation view the half-height alternative
rear-loaded embodiment.
FIG. 8 is a sectional view from line 8-8 of FIG. 7 of the
half-height alternative rear-loaded embodiment.
FIG. 9 is a exploded view of the preferred front-loaded
embodiment.
FIG. 10 is an exploded view of the preferred embodiment in a
rear-loaded configuration.
FIG. 11 is a sectional view from line 11-11 of FIG. 12 of an
alternative front-loaded embodiment using multiple 12-inch drivers
in an opposed-mount throat configuration. This view does not show
the horizontal bracing elements.
FIG. 12 is a front elevation view of the rear-loaded alternative
embodiment as seen in FIG. 11 with the front panel not shown.
FIG. 13 is a sectional view from line 13-13 of FIG. 11 of the
rear-loaded alternative embodiment.
FIG. 14 is a sectional view of another alternative front-loaded
embodiment featuring multiple 12-inch drivers in a "clam-shell"
type of opposed-mount throat configuration. This view does not show
the horizontal bracing elements and is consistent with the view of
FIG. 11.
DESCRIPTION OF THE INVENTION
The current invention consists of a folded exponential-horn
enclosure which is symmetrical in both horizontal and vertical
planes which is contained within a substantially parabola-shaped
outer shell as formed by the rear-channel walls. The overall mouth
size for an 1/8 space horn (as measured at the terminal exit)
required for the given Fc of 38 Hz is approximately 800 square
inches in area (where further waveform expansion presumably takes
place outside of the enclosure, as is typical), and therefore, the
invention in its optimal state is approximately 39 inches in
height, which is also determined to present the optimum height for
the effective propagation of a top-mounted midrange and/or high
frequency horns to a seated audience.
The preferred embodiment of the invention can be seen in FIGS. 2,
3, 9 and 10. The preferred embodiment of the invention embodies two
15-inch drivers needed to achieve the appropriate channel size at
the rear of the enclosure. The invention, being symmetrical, is
capable of being constructed as single full-height unit or being
equally divided in the horizontal plane forming separate
half-height enclosures each employing a single 15-inch driver 10,
intended to be stacked when in operation, and thereby achieving the
optimum overall mouth size. In the present disclosure, the
dual-driver single unit version is referred to as the preferred
embodiment, and the half-height versions as the alternative
embodiments.
The half-height embodiments seen in FIGS. 5 though 8 are considered
a desirable modification of the current invention specifically for
use in PA-type applications for reasons of easier portability. The
full-height embodiment is considered desirable in the case of
domestic use where appearance is presumably more important. In the
present disclosure, it can be assumed that the same elements in
both the full and half-height embodiments are functionally
equivalent when present in the half-height embodiments. Referring
to FIGS. 6 and 8, this is most apparent in viewing the half-height
embodiments shown in cross-section.
The overall throat cross-sectional area was selected as a best
match for the reduced footprint size requirement, reduced throat
distortion, and the desired low frequency response. The current
invention is disclosed in the drawings as being constructed of 3/4
inch thick panels.
Exponential expansion rates are used exclusively. The initial
throat expansion rate is 50 Hz or an exponential area doubling
length of 16 inches, and the terminal exit channel is 38 Hz or an
area doubling length of 19.6 inches. The throat horn pathway is
best seen in FIGS. 1 and 3. The preferred embodiment throat cavity
opening 7 area is approximately 78 square inches per 15-inch
diameter driver 10, which presents an equal match to the respective
throat area. The preferred embodiment throat cross-sectional area
is 13 by 6 inches.
Referring to FIG. 1, the preferred embodiment of the invention is
shown in cross-section as derived from line 1-1 of FIG. 2. The view
of FIG. 1 does not include the horizontal braces 16, 19, 20, 21 for
clarity. The horizontal braces 16, 19, 20, 21 are shown separately
in FIG. 4, which is derived from line 4-4 of FIG. 3.
The 15-inch driver embodiments allow for the inclusion or exclusion
of the void spaces to be added or subtracted from the available
back chamber volume (Vb). The void spaces are divided into two
groups, the large vertical areas associated with the sides of the
throat channels 17, and the smaller void areas 18 associated with
the vertical expansion of the throat channels. Without treating the
rectangular back chamber area, the maximum treated volume of the
combination of back chamber and all void spaces is 3.2 cubic feet
per driver, and the minimum of the back chamber proper and the
smaller void spaces is 1.8 cubic feet per driver. These values
provide a range which most drivers capable horn loading inside of
the available throat area can be effectively annulled in at the
overall Fc of the horn. In this disclosure, treating refers to the
practice of filling the void spaces with a fibrous absorptive
material (such as fiberglass) which allows for up to a 25% increase
in effective volume to be achieved. In the drawing figures, when
present, the void cavities 17, 18 are shown completely filled with
a fibrous sound absorptive material representing the maximum volume
of available void space.
In the current disclosure, a specific range of suitable drivers
with appropriate Thiele/Small parameters for horn loaded operation
within the stated minimum and maximum volumes have been selected,
and the two groups of void space volumes forming "steps" in
available Vb, and two corresponding groups of suitable drivers to
be used, the large throat/large Vb drivers, and the small
throat/small Vb drivers. The invention is capable of accommodating
either group of drivers with regard to the void spaces included or
excluded from the Vb, and the treating thereof. In most cases of
the large throat/large Vb drivers, at least a minimal treatment of
the back chamber proper is necessary, such as a single layer of
material along the bottom. The void areas 17, 18 are optionally
connected to the back chamber via baffle 8 cutouts as is typical in
the art.
The wide selection of drivers available in the 15-inch size class
allows for additional configuration elements to be applied to suit
the needs of a particular application. For example, when extreme
sensitivity is desirable, the two drivers may optionally be wired
in parallel, and when extremes of power are required, the drivers
may be wired in series. Variances in optimal throat size for
highest efficiencies or providing upper band-pass limiting within
the maximum available area may also be easily accommodated by the
use of the removable driver mounting board 9 employing the desired
cavity opening area.
Referring to FIG. 10, the preferred embodiment is shown in an
alternative rear-loaded configuration. Since the passage of
upper-bass frequencies is not generally desirable in rear-loaded
horn applications, the use of a front-cavity filter 23 is used to
add a capacitive and controllable limit to the upper frequency
range from passing through the horn. A possible front-cavity filter
and mounting board assembly 23 is shown perspective form in FIG. 10
and in cross-section in FIG. 8. A cavity filter could also consist
of simply stapling a piece of sound absorbing material to a driver
mounting board 9 over the cavity-opening and mounting it to-the
baffle board 8. The half-height version of the rear-loaded
alternative embodiment is shown in FIGS. 7 and 8.
The terminal throat channel splitting wedges 4, as seen in FIGS. 1
and 3, bifurcate the propagated waveform traveling rearward from
the throat channels into equal vertical halves, and turn each half
of the propagated waveform 90 degrees from the center in opposite
directions. The splitting wedges 4 are hard-surface waveform
reflectors arranged with a 45 degree front-facing surface angle.
The terminal throat channel splitting wedges 4 are present in all
of the embodiments shown in the drawings.
The rear-most outer side channel walls 3 behind the terminal
splitting wedges 4 are arranged specifically at angles so that the
sound waves reflect off of them in a consistent and appropriate
direction selected to approximate the best-case path to continue
propagating down the remaining exit channels. The angles were
derived from using mirror reflectors and a light source and
therefore presume straight-line "ray" propagation. This technique
presumably provides less inter-channel reflections from the channel
sidewalls and the associated turbulence normally encountered in
folded horns. This positive effect is compounded by the nature of
the hard-surface reflections and allows for a wide operating
frequency bandwidth as well as preserving a significant degree of
wave phase relationships. Additionally, the forward-canted exit
splay angles present a better propagation path for shorter
wavelengths, and combined with the short overall horn path length,
and relatively large throat area, the ability to pass upper-bass
frequencies is increased, the remaining limitation being dictated
primarily by the mass roll off of the respective drivers employed.
The natural wide band pass capability of the current invention is
rendered somewhat moot when used in a rear-loaded configuration, of
course, where upper band-pass capability is intentionally
suppressed to prevent comb filtering effects. The horn pathway can
be seen in FIG. 1 as described by dotted line 28.
Referring to FIGS. 1 through 4, the current invention consists of
three separate assemblies, one being the exterior channel wall
assembly, consisting of mirrored parts 1, 2, 3 including the
splitting wedges 4, and second assembly being the interior parts
which make up the back chamber and throat channel assembly. The
back chamber consists of parts 8, 12, 13 and the top 14 and bottom
15 panels. The third assembly is connective in function and
consists primarily of the horizontally disposed components of the
enclosure. The connective assembly is composed of the top 14 and
bottom 15 panels, along with the horizontal braces 19, 20, 21, best
seen in FIG. 4, which combine the other two assemblies together
into a cohesive operational unit. Additional braces 16, 22 are used
to add structural support, provide attachment points, and reduce
panel vibration.
Referring to FIG. 3, the throat channels are comprised of the
vertical throat sidewalls 5, the vertical baffles 6 and the central
horizontal brace 19. In the preferred embodiment, the rectangular
throat cavity opening 7 is horizontally centered and is arranged
with the long sides arranged vertically in the baffle board 8. In
the alternative embodiment drawings seen in FIGS. 11 through 14,
the baffle board 8 is not present.
The exterior channel walls 1, 2, 3 are arranged by function in a
substantially parabolic arrangement and form the outside walls of
the horn terminal (or exit) channels. The general pattern formed by
the exterior channel walls is an approximate parabolic curve when
viewed from the top which is a characteristic feature of the
present invention. The throat channels exhaust into the focus of
the modified parabola formed by the exterior channel walls. The
exterior channel wall can be considered as being arranged in a
mirrored fashion at the center axis of the parabola.
The interior walls of the terminal exit channels are formed by the
outside vertical walls of the back chamber 12 and throat assembly
external side walls 11. The distance of separation between the
internally exposed rear-most channel walls 3 and the throat side
channels 5 is 1/2 the horizontal width of the throat channel, in
the case of the disclosed invention. This separation forms the
bifurcated throat sections of the corresponding terminal channels
in which the width on axis is also not less than 1/2 the width of
the throat channel.
The intermediate terminal channel outer wall 2, being shown in the
drawings as a planar element, is angled at 45 degrees to correspond
to the right angle of a corner. The inner portion of the
intermediate channel is formed by the throat assembly side walls
11. The space of separation between the inner and outer
intermediate channel walls is determined by the exponential
expansion rate of 38 Hz.
The terminal exit is formed by the exterior side channel walls 1,
which is canted slightly forward from the angle of intermediate
channel outer wall 2 to cooperate with the perpendicular back
chamber side walls 12 forming the exit channel boundaries. The horn
terminus is approximately 800 square inches when the channels are
enclosed by the top 14 and bottom 15 panels.
The combination of the rectangular-shaped vertical throat channel
exhausting horizontally rearward along the central axis of the
enclosure, perpendicular to the splitting wedges 4, the interior
channel sides 5 along the throat section, and the angles rear-most
side wall reflecting panels 3, the 45 degree channel walls 2, and
the forward-splay angles of the terminal exit panels 1 give the
invention a characteristic operational feature and also give the
invention a unique appearance when viewed from the top or back.
The preferred embodiment back chamber is defined in the rear by the
apertured baffle board 8, and in the front by the front panel 13.
The back chamber sides 12 are axially arranged front-to-back and
provide an attachment surface for the front panel 13, in
combination with glue blocks or mounting strips 22 as seen in the
drawings for the same purpose, as well as structural support. In
the alternative embodiments using an opposed-throat configuration,
the baffle board 8 as seen in the preferred embodiments is not
present. The opposed-throat configurations instead use horizontally
extended throat channel side panels 5 with the appropriate throat
cavity openings 7 in opposition. The preferred embodiment back
chamber is described in this disclosure as being substantially
rectangular in shape due to the generally parallel side walls 12,
however, it should be noted that the back chamber could be modified
to a different shape such as a trapezoid shape, depending on the
particular application.
The front panel 13 is removable in all embodiments, and provides
access to the interior of the back chamber. As an added utility,
the removable front panel 13 allows for the ability to replace it
with an appropriately apertured baffle, permitting the front
mounting of drivers for rear-loaded operation. Since the front
panel 13 is interchangeable, additions or modifications can be made
to it to enlarge the back chamber volume by the addition of a frame
or extension as desired, or provisions can be made on the front
panel 13 to reduce the available volume if so desired.
In the case of the preferred front-loaded embodiments, the front
panel 13 could also be modified to include an external heat-sink
element for high output purposes, as it is disposed in close
proximity to the magnet structure of each driver.
In the preferred embodiment, as seen in FIGS. 2-4, 9 and 10, the
front horizontal back chamber brace 16 is used to suppress
vibration of the front panel 13, and is shown with multiple
apertures primarily to reduce weight and consequently allow
acoustic coupling. The front horizontal brace 16 is not present in
the half-height embodiments or in the alternative embodiments.
Referring to FIG. 4, the horizontal channel braces 19, 20, 21 are
shown. Where three tiers of horizontal bracing is described in the
drawings of the preferred embodiments as providing the maximum
structural support without sonic degradation, it is conceivable
that the braces 19, 20, 21 may be reduced to two tiers or less, and
otherwise be arranged in a vertically staggered manner to reduce
weight. The functional requirement of the horizontal braces 19, 20,
21 is to provide a degree of lateral support for the channel walls
and to suppress panel vibration. The function of the horizontal
back chamber brace 16 is to suppress vibration of the back chamber
walls, baffle board 8, and front panel 13.
Referring to FIGS. 11, 12 and 13, an alternative embodiment is
shown consisting of an opposed-throat configuration using four
12-inch drivers 24. In the alternative embodiments shown in FIGS.
11 through 14, the external channel wall group remains consistent
with the preferred embodiments and only the back chamber and throat
assembly is adapted for the alternative configuration, and the
horizontal brace elements 19, 20, 21 are not shown. It is
contemplated that certain modifications could be made to further
enhance the utility of the alternative embodiments. An illustrated
modification shown in the drawings is that the front panel 13 has
been effectively extended forward by oversetting the top and bottom
panels, compared to the preferred embodiments. The opposed throat
configuration provides-the-ability-to incorporate a heat-sink
assembly on the outside of the back chamber through the interior
horn channels. In the alternative embodiments as seen in FIGS. 11
through 14, the back chamber is comprised of the total volume of
space that is shown as partitioned void spaces 17, 18 in the
preferred embodiments. FIG. 12 shows the alternative embodiment
with the front panel 13 not shown.
FIG. 14 shows a cross-sectional view of yet another alternative
throat arrangement commonly called a "clam-shell" throat
configuration, again using four 12-inch drivers 24. The view in
FIG. 14 is consistent with the view in FIG. 11, however, it assumes
a modified back chamber and throat configuration which is not shown
in the other drawings. The alternative 12-inch driver
opposed-throat embodiments generally present a simplified form,
lacking the necessity of a baffle board 8, as the function is
combined in extended throat sidewalls 5. In the case of the
alternative 12-inch driver embodiments, certain parts are added,
although not necessarily required, for functionality. Specifically,
in FIGS. 11 though 13, the addition of cavity opening splitting
wedges 26 and an extended central horizontal brace 25 are
disclosed. As shown in FIG. 14, the clamshell-throat embodiment
includes a throat terminating planar element 27 which would replace
the cavity opening splitting wedges 26 seen in FIGS. 11 through 13.
The alternative opposed-throat embodiments allow for a great deal
of flexibility as to viable throat configurations without departing
from the inventive concepts presented herein.
The alternative embodiments could include the use of six 10-inch
drivers in an opposed throat configuration, employing three drivers
per side, instead of the four 12-inch drivers. This configuration
would seem to be particularly applicable as music instrument
speakers. It will be expected that the alternative embodiments may
not be as readily adaptable to various driver applications as
compared to the preferred embodiments. It should also be
anticipated that the alternative embodiments could also include
half-height versions of the examples shown in the drawings.
It will be understood by those experienced in the art that the
overall Fc of the terminal horn dictates the size of the enclosure;
therefore, the cabinets shown may be made larger or smaller than
the preferred embodiment depending on the target Fc of the
alternative application, and alternative drivers may be substituted
to suit a particular need.
It should also be realized that the alternative-use configurations,
especially in the rear-loaded direct radiator embodiments, the
front panel 13 could easily accept multiple drivers or combinations
of drivers which are not shown in the drawings. The possible
alternative configurations are therefore many and should not be
limited to only that which is defined in the drawings.
Whereas this disclosure depicts one specific type of manufacture,
it should not be limited to materials and processes that utilize
only straight planar elements, such as plywood and the like. It
should also be noted that while straight lines have been used for
describing the various horn channels and reflectors, an alternative
and perhaps better embodiment could utilize curved or concave
elements which would promote an even rotational angle or
approximate a true exponential curve more closely.
While in accordance with the provisions of the Patent Statutes, the
preferred forms and embodiments have been illustrated and
described, it will become apparent to those skilled in the art that
various changes and modifications may be made without deviating
from the inventive concepts set forth above.
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